No abstract

No abstract

This Letter deals with the antireflective properties of top-patterned pyramids, looking like sand castles, bi-periodically repeated on a silicon surface. It is demonstrated numerically that such an original pattern allows a dramatic spectral and angular broadening of the antireflective efficiency. Design examples are given for wavelengths ranging from 0.5 microm to 5 microm and incidence angles of 30 degrees and 45 degrees. Applications of such antireflective surfaces on photodetectors and solar cells are soon expected.

An experimental process is proposed to fabricate random rough surfaces which statistical properties can be controlled and tuned. The theoretical approach is developed opening the way to simple, low cost and large surface patterning method. A photoresist is exposed to a speckle pattern created from an argon ion laser. The laser beam has previously been shaped using a digital micromirror device, allowing controlling the correlation function of the speckle. The patterned resist is then transfer by reactive ion etching onto silicon, allowing use for optoelectronics applications. Examples of surfaces, fabricated with Gaussian and non-Gaussian (modified) correlation functions are shown and demonstrate an agreement with theoretical predictions.